The invention relates to a method for production of a film which has a surface made of synthetic material, known as the outer surface, which is designed to be on view, and a symbol or pattern, which prevents reproduction by optical scanning, and is visible from this outer surface side. The invention also extends to a film of this type, a protective transfer comprising a film of this type, a method for protection of a document or other element by means of a film of this type or a transfer of this type, and a document thus protected by means of a film of this type.
In order to prevent reproduction by optical scanning (photocopy, photograph, scanner, etc) of official documents such as bank notes, credit cards, cheques, identity documents, etc, it is already known (FR-2 429 292) to use a paper or a printing support comprising iridescent patterns which produce visual effects which vary according to the direction of observation. This iridescence is obtained by adding an iridescent composition to the surface of the paper or printing support.
However, in this method, simply scratching the surface makes it possible to remove the iridescent composition of an original. In addition, the same iridescent patterns can be produced on the support used for reproduction of the document, before or after this reproduction.
In addition, use of these iridescent compositions is costly, and complicates considerably the production of the paper or printing support, and of the document obtained.
EP-A-0,429,782 describes micro-structures such as holograms on printed bank notes. In order to use these micro-structures, an embossed security profile is used, which has a specific number of embossed lines recessed and/or in relief, and flat intermediate spaces. The security profile is inserted by embossing, after application onto the note of a sheet comprising the security micro-structure. It should thus be noted that all the facets defined by the embossing lines have the same condition of glossiness.
The object of these micro-structures is to combat forgery, and not to prevent reproduction by optical scanning. In addition, production of these micro-structures is problematic and costly.
The object of the invention is thus to eliminate these disadvantages, by providing a more efficient method for protection of documents against reproduction by optical scanning. The object of the invention is also to provide a method of this type, which is simple, cheap, and does not complicate the production either of the printing support, or that of the document itself.
For this purpose, the invention relates to a method for protection of a surface of a document, against reproduction by optical scanning, wherein there is applied irreversibly to this surface at least one film which has an imprint recessed in one surface, known as the outer surface, which is on view, of a layer of synthetic material of the film, this imprint having a surface condition which is more glossy than the remainder of the said outer surface, this imprint forming a symbol or pattern which is on view, and prevents reproduction of the document by optical scanning.
The expression xe2x80x9cthe film is applied irreversiblyxe2x80x9d means that the film can then no longer be separated from the document without damaging or destroying the film and/or the document.
Throughout the text, xe2x80x9can imprintxe2x80x9d means one or a plurality of combined or separate marks of any shape which are recessed. This imprint forms a symbol (which in particular can be character, and/or a group of characters, and/or a letter, and/or a group of letters, and/or a word, and/or a group of words, and/or a drawing, and/or a group of drawings, and/or a combination of these symbols), or a pattern, ie. a plurality of symbols which can be repeated regularly or non-regularly.
Throughout the text, a surface is said to be glossy when it has glossiness in white light at 85xc2x0 (angle of incidence of the light), for example measured on the BYK GARDNER brightness measurer, greater than 50%; a surface is said to be non-glossy when it has glossiness in white light at 85xc2x0 of less than 50%, a surface is said to be matt when it has glossiness in white light at 85xc2x0 of less than 30%. In the case of layers produced by printing, and in particular by silk-screen printing, it is known that the glossiness is associated with the surface condition. Thus, a surface is more glossy when its surface condition is less rough. The glossiness or dullness of a surface can thus also be evaluated by measuring the roughness.
Advantageously and according to the invention, the film is applied to the surface of the document by means of an adhesive. Advantageously and according to the invention, a film formed from a plurality of layers is used, the layer which has the said outer surface being a matt polyurethane layer which is provided with an imprint which is recessed and has a glossy surface condition.
The object of the invention is also to provide means for implementing this method for protection, ie. a film which is designed to be used in this method for protection, a protective transfer, and a method for production of a film of this type, and of a protective transfer of this type.
Throughout the text, xe2x80x9ctransferxe2x80x9d means a product which comprises at least one film and one support sheet, and which is designed to permit application of the film onto a surface of a document to be protected, the film being transferred from the support sheet onto the surface of the document by contact and activation of an adhesive which bonds the film and the surface of the document, and separation of the support sheet.
The invention thus also relates to a method for production of a film which has a surface made of synthetic material, known as the outer surface, which is designed to be on view, and a symbol or pattern which prevents reproduction by optical scanning, and can be seen from this outer surface side, wherein
a support sheet with a non-glossy surface is selected, onto which the synthetic material of the said outer surface of the film does not adhere;
on the said non-glossy surface, a first, discontinuous imprint is produced by means of a printing composition, which, after hardening and/or drying, forms a varnish which adheres to the said non-glossy surface, this varnish having a surface condition which is more glossy than that of the said non-glossy surface, and which in particular is a glossy surface condition;
subsequently, on this first imprint, there is produced a second continuous imprint of a printing composition, which, after hardening and/or drying, forms a layer of synthetic material, one surface of which, which is in contact with the said non-glossy surface and with the varnish, constitutes the said outer surface of the film, which does not adhere to the said non-glossy surface, this layer of synthetic material being compatible with the varnish of the first imprint, and not adhering to this varnish, or adhering to this varnish less strongly than this varnish adheres itself to the said non-glossy surface of the support sheet, such that, after subsequent separation of the film and the support sheet, this varnish continues to be associated with the support sheet, the said outer surface of the film having a more glossy imprint, and in particular a glossy imprint, which is left by the varnish recessed in the said outer surface, and forms a symbol or pattern which is on view, and prevents reproduction by optical scanning; and
production of the film is completed above the said layer of synthetic material.
Advantageously and according to the invention, as the printing composition for the first imprint, there is used a bonding agent comprising a rubber derivative which forms a glossy varnish, and in particular a blending base comprising a rubber derivative for silk-screen printing ink.
Advantageously and according to the invention, as the printing composition for the second imprint, there is used a two-component mixture which can be polymerised in situ, which, after polymerisation, forms a polyurethane layer.
Advantageously and according to the invention, a printing composition for the second imprint is selected, which provides a layer of transparent synthetic material.
In addition, advantageously and according to the invention, a matt polystyrene support sheet is used. In addition, preferably, advantageously and according to the invention, an opaque support sheet is used.
Advantageously and according to the invention, the varnish obtained from the first imprint is allowed to harden and/or dry completely, before the second imprint is begun.
In addition, advantageously and according to the invention, the first and second imprints are produced such that the thickness of the varnish formed by the first imprint is between one third and two thirds of the total thickness of the layer formed by the second imprint, and in particular approximately half, of the total thickness of the layer formed by the second imprint. Advantageously and according to the invention, the second imprint is produced such that the thickness of the layer formed is less than, or approximately 20 xcexcm.
According to a variant of the invention, advantageously and according to the invention, in order to complete the film, there is also produced at least one coloured discontinuous additional layer, which can be seen by transparency, through the layer which is formed by the second imprint.
Advantageously and according to the invention, in order to complete the film, at least one continuous additional layer is produced.
Advantageously and according to the invention, each layer of the film is produced by printing of a two-component printing composition which can be polymerised in situ, which, after polymerisation, provides a polyurethane layer.
Advantageously and according to the invention, the film is covered with a continuous adhesive layer, such that a protective transfer is produced together with the support sheet, the film and this adhesive layer. The film is thus a transfer film which can be applied to the surface of a document, to which it adheres, in order to cover the latter at least partially and protect it against reproduction by optical scanning. The invention thus also provides a method for production of a protective transfer. Advantageously and according to the invention, a transparent adhesive layer is used. Advantageously and according to the invention, the adhesive layer is applied by printing of a composition which, after hardening and/or drying, is selected such as to form a contact adhesive (pressure-sensitive self-adhesive), and/or an adhesive which can be activated thermally.
Advantageously and according to the invention, the first imprint and/or the second imprint is produced by silk-screen printing. Advantageously and according to the invention, the method as a whole is implemented by means of silk-screen printing.
The invention also relates to a film obtained by a production method according to the invention. The invention thus extends to a film which has a surface made of synthetic material, known as the outer surface, which is designed to be on view, wherein it comprises an imprint provided recessed in the said outer surface, and with a surface condition which is more glossy than the remainder of the said outer surface, such as to form a symbol or pattern which prevents reproduction by optical scanning, and is visible from this outer surface side.
Advantageously and according to the invention, the film consists of a plurality of layers, the layer which has the said outer surface being a matt polyurethane layer which is provided with a recessed imprint which has a glossy surface condition. Advantageously and according to the invention, the various layers of the film are transparent.
The invention also extends to a protective transfer, comprising the film according to the invention. The invention thus relates to a protective transfer comprising a support sheet and an adhesive transferable protective film which is supported by the support sheet, such as to permit separation of the film and the sheet, and application and adhesion of the protective film on a surface of a document, in order to cover the latter at least partially and protect it, this film comprising an adhesive surface which is designed to be applied to the surface of the said document, and an opposite surface made of synthetic material known as the outer surface, which is designed to be on view when the film is applied to the said surface. According to the invention, the transfer is characterised in that the said outer surface of the film extends in contact with a non-glossy surface of the support sheet, and has a symbol or pattern which prevents reproduction by optical scanning, is designed to be on view on the said outer surface side, and is obtained from a recessed imprint provided in the said outer surface, this imprint having a surface condition which is more glossy than the remainder of the said outer surface, this imprint being left, after separation of the support sheet and the film, by a varnish which is printed discontinuously on the said non-glossy surface with which this varnish continues to be associated.
Advantageously and according to the invention, the support sheet is a matt polystyrene, and at least one layer of the film which has the said outer surface is a polyurethane layer. Advantageously and according to the invention, the film is transparent, such that it makes it possible to see inscriptions provided on the surface of the document to which it is applied, and/or on its surface in contact with this surface, and/or in the interior of the film.
In a method of protection according to the invention, a film according to the invention is used, obtained by a production method according to the invention. More particularly, advantageously and according to the invention, in order to apply the film to the document, a protective transfer according to the invention is used, which is obtained by means of a production method according to the invention.
The invention also extends to a document thus protected. The invention thus relates to a document which has a surface protected against reproduction by optical scanning, wherein it comprises a film which is applied to the said surface of the document, such as to have an outer surface which is on view, and an imprint recessed in the said outer surface, this imprint having a surface condition which is more glossy than the remainder of the said outer surface, such as to form a symbol or pattern which prevents reproduction of the document by optical scanning. Advantageously and according to the invention, the film is a film obtained by means of a method according to the invention.
It should be noted that, according to the invention, the imprint which is provided on the outer surface of the film is formed and obtained without added material. Thus, it cannot be removed from an original by scratching. Consequently, reproduction by optical scanning, of the inscriptions of the original which are disposed beneath the symbol or pattern formed by this imprint, is impossible, as is that of the symbol or pattern itself. It should also be noted that copying the original symbol or pattern on a film is rendered particularly problematic, since this sign or pattern is obtained indirectly from an imprint formed on the support sheet, rather than on the film itself.
Advantageously and according to the invention, the film used is a multi-layer anti-forgery film, in particular of the type described in EP-0 271 941.
The invention also relates to a method for protection, a film, a protective transfer, a method for production, and a document comprising in association all or part of the characteristics previously described, or described hereinafter.